This invention concerns apparatus for treating hypothermia in humans by hot air inhalation and is mainly addressed to devices which may be qualified as portable and self-contained types, in other words, field units designed for use at the site of an accident.
Experiments have shown the usefulness of supplying heat by pulmonary channels to an accident victim in a state of hypothermia.
Indeed, the human body can be deemed to consist of two main parts in terms of thermal regulation. The most sensitive part or thermal core, is that part the temperature of which is normally maintained at 37.degree. C., said part including the brain, heart, liver and so on. The second part may be considered as peripheral to the first and can tolerate variable temperatures, given the organic functions to be maintained and the capacities for interaction with the body's environment. Said second part basically includes the muscles and limbs.
A significant temperature differential between these two main parts of the human body is thus acceptable, provided the temperature of the thermal core itself does not fall below 30.degree. C.--a temperature below which the heart begins to malfunction and may even stop.
Experiments have shown that heat must mandatorily be provided to the thermal core of the human body to keep the vital organs involved in optimal working order, enabling any localized hypothermia at the perimeter or second part to be countered.
It has been observed that introducing hot air directly through the lungs makes it possible to meet this requirement, provided the hot air is otherwise sufficiently moistened to preclude the risk of bronchial spasms and of drying out of the respiratory channels.
Several solutions have already been proposed in view of providing hot and humid air for this purpose.
One such solution consists in using an external combustion system such as a hotplate or burner to heat a water vessel and produce vapor for inhalation by the patient.
This procedure can be dangerous however, as the vapor cannot be temperature controlled and would burn the respiratory channels.
Moreover, the operation of such a device requires a stable, horizontal position which is often not realizable in practice, since hypothermia usually occurs as the consequence of an accident in a difficult-to-access or obstructed site.
In addition, the use of a burner, commonly involving a store of combustible gas, introduces a hazard which cannot be overlooked.
Another such solution calls upon the exothermal reaction of lime when exposed to water. However, such exothermal reaction does not lend itself to accurate temperature control of the reaction gas and therefore does not meet the stated requirement of supplying a mixture such as humified air at a constant, controlled temperature to place the subject in a receptive, relaxed and expectant state most propitious to the treatment of accident-caused hypothermia.
Besides, the difficulty of practically implementing such an approach in the context of a traffic accident or a mountain rescue operation is obvious. And furthermore, such as approach does not afford the kind of "stand-alone" capability required in practice for the prevention and control of hypothermia.